We have focused our study on the molecular mechanism leading to the proliferation of Plasmodium falciparum in erythrocyte and its subsequent sexual development. I. Protein Kinases, in response to signals, act as transducers through phosphorylation of specific proteins to control many metabolic and developmental events of cells. We have cloned the casein kinase I and II gene from a Plasmodium falciparum cDNA library. Casein kinase II (CKII) catalytic subunit is fully characterized, which is recently expressed in a prokaryotic system in order to study its catalytic activity. CKII gene shares about 60% homology with other eukaryotic analogs. The protein kinase gene (cGMP-dependent protein kinase) of the cyclic GMP effector pathway. The partially identified sequence of 360 amino acid residues indicates the homology to other eukaryotic analogs is about 35%. The gene is located on chromosome 14. II. Small GTP-binding proteins. To investigate the secretory process in Plasmodium, we decide to examine whether small GTP-binding proteins, the major molecular components of secretory machinery conserved throughout eukaryotes, may play a role in protein secretion and translocation. Small GTP-binding proteins are a group of 20-30 kDA Ras-like proteins and involved in regulation of cell proliferation and differentiation. We have identified a gene encoding a Ras-related protein from the erythrocytic stage cDNA library. Cellular localization of Plasmodium protein may help us to unravel the protein transport mechanism of parasite and its interaction with host. III. Stress proteins. The genes encoding two major heat shock proteins, hsp60 and hsp90, have been cloned and hsp60 fully characterized. Both Plasmodium hsps exhibit strong homology with other eukaryotic analogs.